Viruses in the Lake Baikal Ecosystem

The most voluminous and oldest fresh lake Baikal is inhabited by diverse and numerous representatives of viral life. Its pelagic waters contain phages both in surface layer, as well as in water mass itself till the maximal depths in all three through (Southern, Central, Northern Baikal). The most of baikalian phages belong to Caudovirales. Siphoviridae, Podoviridae, and especially Myoviridae practically dominate both virioplankton and natural biofilms of the lake. The number of phages is rather significant - up to 107 ml-1 in upper layers (0-25 m) of water during seasons of mass development (March-April, August-October). Seasonal dynamics of number of phages follows the number dynamics of heterotrophic bacteria and phototrophic cyanobacteria. Lysis of significant share of bacteria provides phages with important role in bacterial loop of trophic net of the lake.